Sidewalk Vault Lights

One of the few remaining sidewalk vault light panels in Butte, Montana, 2013.

One of the few remaining sidewalk vault light panels in Butte, Montana, 2013.

Invented in 1845 by Thaddeus Hyatt, sidewalk vault lights started being used in urban areas beginning around the 1850s and continued to be popular into the 1930s. The first vault lights were engineered to have glass blocks placed into a cast-iron framework. Later, with the introduction of Portland cement, setting them into reinforced concrete panels was more common.

Sidewalk vault light panels in San Francisco, California, 2015. This is one of the most intact panels I have ever seen.

Sidewalk vault light panels in San Francisco, California, 2015. This is one of the most intact panels I have ever seen.

Thaddeus Hyatt's Pendant Lens Patent illustrating how the light is distributed.

Thaddeus Hyatt’s Pendant Lens Patent illustrating how the light is distributed.

These “lights” provided a way to get light into the useful basement and void areas under the sidewalks. This also made the space rentable in some cases. First attempts at vault lights proved unfruitful because the design basically allowed a single shaft of light to shine straight down into the space below. With Hyatt’s invention, the design incorporated a prism shape (“saw-tooth”) on the underside while the surface above remained smooth to walk across. This provided a way for the light to be directed over a broader area in the dark underground.

Brown Bros. Manufacturing Co. catalog advertising the "Hyatt" refracting lens. Sidewalk vault technology was primarily geared toward business owners in urban areas.

Brown Bros. Manufacturing Co. catalog advertising the “Hyatt” refracting lens. Sidewalk vault technology was primarily geared toward business owners in urban areas.

Faced with the pressure of typical sidewalk use over the years, many glass blocks have been broken and loose seals have caused them to fall out entirely. For obvious reasons, this creates hazardous walking conditions as well as allow water and other debris into the space below. Yet repairing virtually unnecessary sidewalk vault lights can be considered costly and challenging when compared to the simple solution of removing or covering them with asphalt or concrete. The need for an experienced contractor and locating supplies and fabricators for the glass blocks and sometimes the cast-iron panels are not the only challenges. Today building code and load requirements are quite different from the 19th and early 20th centuries; especially when taking into consideration that the void space under the deteriorated sidewalk lights might need structural work as well.

A glass "saw-cut" block from a sidewalk vault light panel in Missoula, Montana, 2012.

A glass “saw-cut” block from a sidewalk vault light panel in Missoula, Montana, 2012.

However, repair and maintenance of these beautiful architectural features is not as difficult and expensive as it may seem. Restoration projects in various urban areas show that, “sensitively rehabilitated vault lights can continue to provide architectural and historic character to the urban streetscape while serving their original function of naturally illuminating basement spaces” (Stachelberg and Randl, 2003).

Stachelberg, Cas, and Chad Randl                                                         2003 Historic Glass Number 2: Repair and Rehabilitation of Historic Sidewalk Vault Lights, Preservation Tech Notes National Park Service U.S. Department of the Interior, Washington D.C.

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Photo Post

Door into the sidewalk void from the basement. A concrete block wall can be seen which blocks entrance to the void itself.

Door into the sidewalk void from the basement. A concrete block wall can be seen which blocks entrance to the void itself.

Large, blocked window facing into the sidewalk void from the basement. Window is to the east of the door.

Large, blocked window facing into the sidewalk void from the basement. Window is to the east of the door.

Smaller, blocked window facing into the sidewalk void from the basement. Window is to the west of the door.

Smaller, blocked window facing into the sidewalk void from the basement. Window is to the west of the door.

All rights reserved. Reproduction or sharing of images on this site are strictly prohibited without written consent from the blog owner.

Historic American Buildings Survey (HABS) – Part 2

In the last post, we looked at a little bit of background about the Historic American Buildings Survey (HABS) and some of the guidelines for taking measurements for a HABS quality map in a historic structure. In Part 2 here, we will look at the guidelines for how the final drawings should be completed and look at an example from the Missoula Historic Underground Project.

When producing the final drawing of a HABS map, it is best to first use graphing paper. For the Missoula Historic Underground Project, we typically used 8 squares per inch. If the drawing will be submitted to the Library of Congress for adding to the collections, pre-printed sheets of HABS standard mylar are available from the HABS office upon request. The drawing can then be transferred onto this mylar paper to remove the graph paper lines for a cleaner look. Some of the other requirements are:

  • use of archival pens, lines in black, and measurements in colored pencil (generally red) to set them apart from the sketch;
  • measurements are placed outside the lines, not inside the drawing and are written perpendicular to the dimension line;
  • the drawing must be centered on the sheet both horizontally and vertically;
  • the use of standard architectural symbols is required for consistency;
  • room breaks should be delineated.

Even the text and legend/title box has guidelines that must be followed:

  • All text must be in uppercase letters with no abbreviated words;
  • When using a pre-printed HABS sheet, the title box is already set up but it generally includes such information as- project name, building name, address, site number, map title, date, and who the drawing was completed by.
  • The drawing should include a north arrow as well as the scale box in metric and English.
Plan map for the basement of one of the MHUP sites. (Image is scanned in B&W but the dimensions would be in another color besides black.)

Plan map for the basement of one of the MHUP sites. (Image is scanned in B&W but the dimensions would be in another color besides black.)

Above is an example of a HABS quality map from the Missoula Historic Underground Project.

All rights reserved. Reproduction or sharing of images on this site are strictly prohibited without written consent from the blog owner.

Historic American Building Survey (HABS)

Documenting the spaces when surveying a site for the the underground project is one of the most important steps in the survey process. Maps are carefully drawn in order to understand the scale of the spaces being examined and also to know precisely where features, such as underground doors and windows, are located. Accuracy and attention to detail is critical so we use guidelines that are set up in the Historic American Building Survey (HABS).

Historic American Building Survey Brochure from the National Park Service

Historic American Building Survey Brochure from the National Park Service

The Historical American Building Survey was established in 1933, during the Great Depression, as a means to supply 1,000 architects who were out of work with jobs. What began as a 10 week project has since functioned as a guideline in a standardized format for recording and documenting historic structures. The HABS program is operated by the National Park Service, the Library of Congress and the American Institute of Architects. HABS drawings, as long as they meet the guidelines, can be submitted to the federal database held by the Library of Congress.

The history and collection of HABS documentation can be viewed on the Library of Congress website here.

For the Missoula Historic Underground Project, the standards were followed as closely as resources and the documentation process would allow. For instance, these guidelines for measurements:

  • Measurements should be taken with metal tape measures, to avoid slack in the measurements;
  • Measure in as long and continuous line as possible;
  • Measure to the outside of walls, door and window frames, etc.;
  • Record measurements in metric;
  • Horizontal measurements should be taken 4 feet above the floor.

In the next post, HABS Part 2, we will look at the guidelines for how the final drawings should be completed and look at an example from the Missoula Historic Underground Project.

Sanborn Fire Insurance Maps

These maps were originally created for assessing fire insurance liability in U.S. cities. Today they serve as an important resource for geographic, historic, and urban archaeological research. In 1867 the Sanborn Company began creating these maps by employing the skills of surveyors who performed field surveys for the purposes of recording building footprints and details about each building including property boundaries, building materials, number of floors, and other construction information about the urban infrastructure surrounding the buildings.

Using Sanborn Fire Insurance Maps for historic research is not without challenges. Inaccuracies and omissions based on the cartographer’s point of view make it difficult to make certain conclusions with certainty. Other issues such as map style changes over time, illegibility, and scale variation affecting spatial accuracy are all common issues. While they are indispensible as one resource, caution must be exercised when using these and any type of map in understanding a site’s history.

Sanborn maps for Missoula, Montana document the town’s development for the period spanning 1884-1957. Three representative samples of the same downtown block show the changes to the built environment and urban landscape from 1884-1912.

1884 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

1884 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

1902 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

1902 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

1912 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

1912 Sanborn Fire Insurance Map for the city block encompassing the north side of West Front Street and south side of West Main Street.

Digital Sanborn map 1867-1970 by Proquest UMI, online at http://Sanborn.umi.com; Sanborn: Total Geographic Information by the Sanborn Map Company, Inc., 2003. http://www.Sanborn-map.com/default.htm